Great questions, but I noticed in all the comments about orienteering vs. hiking no one answered your questions.
I have been walking and hiking for about 15 years now, and orienteering for 10. I have had knee problems for many years, and as it turns out I can walk for miles, but cannot run at all. I jog for 50 meters and my knees swell up. Therefore when I go orienteering, I just walk (fairly fast) on the trails of the easier courses, and watch most of the time-conscious orienteers zoom by me. Yes, I never win, but I enjoy the real navigation of new areas.
To the questions, I say!:
>What is it about hiking that interests you?
Hearing the birdies chirpin', the bugs a buzzin', the sun a shinin', and the breeze a blowin. Hello, mother nature, long time no see.
>Is it easy to get started?
Yes. Walk. Up in the hills, or on a walking path, or out in a field, or on a snow-covered mountain, or by the beach. Just walk.
>Is it easy to get hurt?
It is possible to twist an ankle occasionally on slippery rocks or logs, or get stung by a bee or bit by a snake. Possible, not likely.
Are there a great deal of safety precautions?
Never walk off a cliff, piss off a snake, poke a bear with a stick, or jump in a hole.
>How important is equipment?
Pretty important, but common sense and planning are the two most important items before a good hike or orienteering event.
Good boots: INVALUABLE. Good, stiff, high, waterproof boots will save you countless problems on the trail. Keep them polished, well-lubricated, clean, and waterproofed.
Always have water, a whistle, a hat, a knife, a snakebite kit, a compass, enough clothes, and a MAP.
>How do you determine if a hike was successful?
If you are alive and home at the end of the day, and not dead or lost in the woods at night, then the hike was successful.
Take a hike!